Carburetors are devices that can be used to mix fuel with air to power combustion engines. A carburetor may include multiple fluid passages to accommodate fluid flow therein. Certain manufacturing methods such as casting processes or cross-drilling can be used to form parts of one or more of such fluid passages and may temporarily result in a passage being connected to an unintended area, such as a different fluid passage or the environment outside of the carburetor. A plug may be used to close-off or seal openings that would otherwise connect fluid passages to such areas.